Swapping a 6bt into my suburban -- questions for the experts
Sorry for the length.
So I have been working on a plan for quite a while to replace my old 7.4 with a 5.9. I have a 1995 Suburban K2500 3/4 ton with 4l80E, np241 and 4.10's, and recently acquired a 93 5.9 6bt from a dodge 3/4 ton. I have plenty of experience to know I don't know everything I need to, even after reading all the stuff I can find on this board.
So my goals: Decent Fuel economy, moderate power, gobs and gobs of torque.
I would like to keep my 4l80E & np241, but am not so committed as to be stupid.
To do this I get that I need an adapter plate, maybe crank spacer/adapter, flywheel, different torque converter and a transmission controller (thank you forum search). So I have read about the bread truck plate as well as the destroker and the from one diesel conversion. The price of the aftermarket setups is steep, so I am looking at all alternatives before I dive in. My question is what is the angle on the bread truck, I have read everything from 7% to 16%. How and why is it angled? Meaning if the motor was level and the transmission was mounted would it stick the rear of the transmission up X degrees or down? Is it possible to adapt it and remove half or all of the angle? Also, what do you guys think a bread truck adapter is worth, money wise?
If I changed tranny's to one of the dodges (47rh?) can I get the 241 hooked up to it? I already assume my drive line length is going to change, so figured on two new driveshafts.
Also, I am looking at the radiator plan. Currently I have the 7.4l radiator (large 2 core) with the built in oil cooler. Will this keep the 5.9 cool? I would probably not use the built in oil cooler, opting for an external.
I am sure I am missing a thousand other details, but any insight you guys can give me to the above I would appreciate. I am trying to put my shopping list together for the bigger items so I can fabricate and locate everything first.
first thing, it sounds like you are thinking that the "angle" of the breadtruck plates refers to frt/back angle. That plate actually "rolls" the engine or trans sideways. I have that setup in my 72 Bronco, and my son just used it in his 93 S10. Both of ours is installed with the engine straightup with the tranny rotated approx. 10 degrees....using a magnetic protractor on the tranny pan. My trans is an NV4500 and my sons is a powerglide. It does NOT seem to have affected the automatic tranny in any way. I'm assuming that would be a concern of yours......rotating the pan.....resulting fluid problem. So far so good.
If you get a breadtruck plate that is the GM pattern, which most of them were, you would be in good shape. Your 4l80e would bolt right to that plate. In the breadtrucks with the GM auto setups, they incorporated the 400 turbo trans......same bolt pattern as your 4l80e. My son picked up his plate, flywheel, starter, and assorted other parts from Avante Auto salvage out of Georgia. Owners name is Benny and right off I can't remember his son's name, but they are pretty good guys to deal with. That is also where my 4bta came from taht is in my Bronco. Got it about 11 or 12 years ago. I think the plate, flywheel, starter and assort. other parts was right around 700, but don't hold me to that. You can sometimes catch the setup on Ebay for less money, just depends on if you're willing to wait and watch for however long it might take for one to show up. My son isn't prone to having patience, lol
I would imagine that your radiator would be sufficient, depending on how much you plan on turning up your output. My son's first gen 5.9 in his 93 S10 keeps plenty cool, and it is turned up quite a bit for a rotory pump'd engine. His rad. is an aftermarket unit, not sure offhand of the brand/size, but of course is relatively small, having to fit the S10 core support.
Mark......now I have a question for you. I've asked on several boards and have yet to get a direct answer. I am collecting parts for a 5.9 into my 97 K1500 burb. I want to know the difference between frame rail dimensions of a K1500 and K2500 Suburban. Would you measure yours for me.....frame rail height....mine is 8", and that is right by the trans crossmember. The thickness of the steel in that area is .172, measured with a pair of calipers. Can you measure yours and let me know............Thanks.
Also, anything else I can help you with just give a yell. Thanks, Louis
just remembered....Benny's son is Jamie.
Last edited by CumminsBronco; 03-10-2011 at 11:32 AM.
Reason: added info
Awesome, thank you so much for the info. The tranny being rolled to a side makes more sense, I was trying to figure out how something could be angled x degrees front to back when it needs to mate up with a torque converter against the flat flexplate.
So as to your questions, I just got home from work and did some measuring for you.
Height of frame is 8 inches, it stays that way throughout the main part of the truck, from basically the firewall area on back to near the rear axle. I didn't measure beyond that. It is boxed from the front of the truck almost all the way to the transmission crossmember, from the factory it appears. My frame between the firewall and the rear axle again, is right around .20" thick with about .01" variation.
I found a link on another board, and it does appear to be a page from a GM tech spec for a 91 suburban. And it seems about on with what we see. I can't post links yet cause I do not have enough posts, but if you search "3/4 ton suburban frame thickness" on google the forum post will be on the top.
One follow up to the bread truck adapter, does it use a standard Cummins starter and GM flexplate? Or are these specific to the bread truck design?
Thanks for the post and answers, really helps. Let me know what else I might be able to help you with.
both of our starters are Denzo 2 bolt flange style, common to 4bt's. There are some on ebay at this time.....to see, go to item number 120660302300. It is man. part # 228000-0603, and has a buy it now price of 176 dollars, new.
I'm not sure what you mean by standard GM flexplate, but it would be one of Cummins design, in that it would have a bolt pattern common to a 4b or 6b crankshaft, not common to a GM crankshaft.
hope that helps, louis
PS..........thanks a bunch for measureing your frame for me. I have seen conflicting info in charts, etc., and have never had an actual measurement.
Last edited by CumminsBronco; 03-11-2011 at 01:04 PM.
Reason: added conten t
Yea, I actually meant Cummins starter & flexplate, but my brain and fingers aren't always on the same page. Thanks so much for the starter link, I'll have to check it out. Parts hunting I have been, and I have a feeling a lot more in my near future.
No problem on the measurements, let me know if you need anything else.